Studies of broadband coaxial cable distribution plants have shown that secondary, “off-air” RF signals picked up by (or impressed upon) the cable system coaxial cable are carried by the cable shielding as a current, commonly termed a sheath current. This current can result in ingress and egress problems due to openings in the cable outer conductor and/or poor connector attachment, as well as “ghosting” of the displayed image. Also, sheath currents propagate from the outer conductor to the ground soil and/or ground block and can accelerate galvanic corrosion within the cable outer conductor.
Efforts to address the problems associated with sheath current fall generally into two categories. In a first type of device for attenuating off-air RF signals that are picked up and conducted by coaxial cable shielding, disclosed in U.S. Pat. Ser. No. 5,091,707, a filter is formed by wrapping the coaxial conductor several turns around each of two, doughnut shaped, ferromagnetic toroidal cores. In a second type, found for example in U.S. Pat. Ser. Nos. 4,885,555, 5,990,756 and 6,072,125, the conductor makes a single, longitudinal pass through a hollow, ferrite cylinder to provide a choke, wave trap, or the like. However, in order to achieve the required attenuation of approximately 20 db, such devices cannot be packaged effectively for mounting on conventional, multi-port taps where the center-to-center spacing is one inch.
There is a need for a coaxial cable connector device for use in cable TV applications which will effectively attenuate sheath currents on the outside surface of the outer conductor and which are mounted in side-by-side relation on conventional, multi-port taps.